Many products, particularly in the food and pharmaceutical industries, degrade, decay or perish over a finite lifetime. The rate at which such products degrade may depend on the environmental conditions. Accordingly, such products are often inserted into a container under controlled environmental conditions and the container is sealed so as to isolate the products from an environment external to the container and thereby keep the products fresher for longer. On opening such a container for the first time, the products contained within are exposed to the external environment and degradation of the products typically accelerates relative to a rate of degradation of the products when in the sealed container. Accordingly, it is conventional to specify both a shelf life for products contained in a sealed container prior to opening the container and a period within which the products should be used after first opening the container.
A problem with storing products in containers in this way is that, without recording the time of first opening a specific container, it is difficult to determine to what extent the products contained within the container have degraded and, in particular, whether the period within which the products should have been used after first opening the container has expired. In the case of food or pharmaceutical products, consumption of such products after expiry of the period within which the products should have been used after first opening the container may represent a health risk. Various solutions to this problem exist. However, the known solutions may be expensive to manufacture, inaccurate or unreliable.
For some applications, particularly in the oil and gas industries, it is also known that a device may have a finite lifetime or a predetermined service interval. The device may, for example, be configured for insertion downhole or for use in a subsea environment or the like. The device may comprise an assembly, a tool, a tubing string or the like. However, known methods of monitoring the time elapsed from activation of such a device may be expensive, inaccurate or unreliable.